VEXpro Omni Wheels - VEXpro 217-4775, These wheels roll forward like normal wheels, but slide sideways with almost no friction so you can use them to make your robot turn smoothly or build a holonomic drivetrain. Omni wheels from VEXpro are manufactured from glass-filled nylon with high-traction rubber rollers and are compatible with VersaHubs for driving with a sprocket or used with bearings for use on an axle.These omni-directional wheels were designed to give the smoothest ride possible. The dual roller design allows for a constant contact patch with a narrow profile. Each roller is tailored for the individual wheel diameter, and provides the correct, constant radius. These wheels aren\'t \"almost round\" - they\'re actually round.Omni-directional wheel assembly hardware is separate from sprocket mounting hardware. Sprockets are screwed into captive 8-32 standoffs. This allows for easy removal and replacement of sprockets without disassembling the entire wheel, so no more worrying about your whole wheel falling apart just because you wanted to remove the sprocket.This wheel only has a centre bore and does not include mounting holes for sprocket, gear, or hub attachment. VEXpro 217-4775 3.25\" Omni Wheel